The overall goal of this application is to develop ELISA spot assays for various molecules secreted by CD8 memory cells after antigen stimulation, in particular for the cytokines, perforin and granzyme-B. The proposed working hypotheses is that, by detecting the antigen/peptide-induced production of these molecules, ELISA spot assays could be used to study antigen-specific CD8 cell memory in freshly isolated cell populations thereby providing a sensitive measurement of antigen-specific CD8 cell activity in vivo. Cytokine ELISA spot measurements should be particularly informative about the differential effector functions of these cells, which may play as important a role in CD8 cell-mediated host defense mere killing does.